organer

Organer are specialized structures composed of tissues that perform specific functions necessary for an organism's survival and homeostasis. In multicellular animals, organs are grouped into organ systems such as the circulatory, digestive, nervous, respiratory, and musculoskeletal systems. Examples include the heart, brain, liver, kidneys, lungs, stomach, and intestines. Some organs are hollow and facilitate the passage or storage of substances (stomach, arteries, bladder), while others are solid and carry out metabolic, synthetic, or regulatory tasks (liver, heart, pancreas).

Organ structure typically reflects a mix of tissue types—epithelial, connective, muscle, and nervous tissue—that work together. Organs develop during embryogenesis from germ layers and interactions among genes, signaling molecules, and environmental cues. Their function is tightly regulated by hormonal, neural, and local feedback mechanisms to maintain homeostasis.

Clinically, organs are central to health and disease. Organ failure, congenital anomalies, and injuries can threaten life, while organ transplantation, surgical repair, and imaging-based diagnosis are key medical tools. Across species, organ size, composition, and specialization vary according to ecological needs, illustrating evolutionary adaptation and organ redundancy.

As a term in Norwegian and some other languages, organer simply denotes body organs; in music, organ refers to the pipe organ, which is a different concept.